Heil, Tempstar, Comfortmaker, Arcoaire and KeepRite furnaces are built by International Comfort Products, and many of their control boards report faults through the same LED status codes. The code that matters most for the blower is 4 flashes, a limit circuit fault that can trace to a dirty filter, a loose blower wheel or a defective blower motor. Check airflow first, then the motor.
Key Takeaways
- 4 flashes means a limit or flame rollout switch is open, and ICP lists the blower wheel and blower motor among the checks.
- 7 flashes is the lockout that follows when the limit circuit stays open too long.
- 6 flashes is an ignition failure, and 6 + 1 is the lockout after the retries run out. Neither points at the blower.
- A two-digit code is short flashes followed by long flashes, so 6 + 1 is six short and one long.
- Reset times and timing vary by control, so use the label inside your blower door.
Safety note: Gas valve, flame rollout and repeated ignition faults belong with a licensed technician. If you smell gas, leave the building and call your gas utility from outside. Do not jumper or bypass a limit, rollout or pressure switch to keep a furnace running.
How These Furnaces Show Codes
This guide uses two ICP documents: the N95ESN installation instructions (form 440 01 4501 01, service label in Fig. 62) and the N9MP control board diagnostic code table. Their core codes match, with small timing differences noted below. A steady bright-dim heartbeat means the control has 24VAC power and no active fault. A single number is a count of short flashes, and a two-digit code is short flashes, a plus sign, then long flashes.
Not every ICP furnace uses this table. The modulating N95ESU (form 440 01 4600 00) uses red, amber and green LED codes with different meanings: 1 red is a system lockout, 6 red is an open condensate float switch and 7 red is a shorted gas valve circuit. Always confirm against the label on your unit.
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Blower Codes First
4 Flashes: Limit Circuit Fault
A limit or flame rollout switch is open. The blower runs for 4 minutes or until the open switch remakes, whichever is longer. ICP lists these checks: a dirty filter or restricted ducts, a loose blower wheel, a defective blower motor, a restricted or undersized vent, inadequate combustion air, and defective switches or connections. Start with the filter and registers, then confirm the wheel is tight on the shaft and the motor runs. See how to test an ECM blower motor for the full sequence. A flame rollout switch needs a manual reset, and a tripped rollout calls for an inspection before anyone resets it.
7 Flashes: Limit Circuit Lockout
The limit or rollout circuit stayed open too long and the control locked out. The N95ESN label sets that point at 3 minutes with an auto-reset after three hours. The N9MP table sets it at 2 minutes with a one-hour delay. Work through the same list as 4 flashes, because a lockout that returns means the cause is still there.
1 + 2 Flashes: Blower On After Power Up
The unit was powered up during a call for heat, or the call opened during the blower-on delay. The blower runs for 90 seconds. This is not a motor fault if it clears on its own.
Ignition, Pressure Switch and Control Codes
| LED | Meaning | Blower Motor the Cause? |
|---|---|---|
| Off | No power to the control or an open 24V fuse | No |
| Solid on | Control circuitry lockout, auto-resets after one hour | No |
| 2 flashes | Pressure switch did not open | No |
| 3 flashes | Low-pressure switch did not close or reopened | No |
| 5 flashes | Flame proved while the gas valve is de-energized | No |
| 6 flashes | Ignition proving failure | No |
| 6 + 1 | Ignition lockout | No |
| 8 flashes | Gas heating lockout, no auto-reset | No |
| 9 flashes | High-pressure switch did not close or reopened | No |
| 10 flashes | 115VAC polarity reversed | No |
3 Flashes: Pressure Switch Open
This is a venting and draft code. ICP lists a defective inducer motor or low inducer voltage, restricted vent, improper vent sizing, excessive wind, blocked condensate drainage, low inlet gas pressure, and disconnected tubing. The inducer is a separate motor from the blower, and the difference is covered in inducer motor vs blower motor.
6 Flashes and 6 + 1: Ignition
The control tries three more times before locking out at 6 + 1, which auto-resets after three hours. Check for oxide on the flame sensor, a grounded sensor, low inlet gas pressure, a defective hot surface igniter, a gas valve that is off or failed, and poor control ground continuity.
How to Read Stored Codes and Run the Component Test
On the N95ESN control, the furnace must be idle with the heartbeat showing. Briefly connect the TEST/TWIN terminal to the thermostat C terminal with a jumper for 2 to 3 seconds. The control flashes the stored status code four times, then starts the component test. Leaving the jumper on for more than 4 to 5 seconds brings up code 10 instead. Stored codes erase automatically after 72 hours.
The component test is useful for a blower call. The inducer runs throughout, while the igniter, fan, heat speed and cool speed each come on for 10 to 15 seconds. A blower that runs on one speed and not another points to the input for that speed or the motor programming, and a blower that never runs points toward the motor or its power and control wiring.
Which Motor Your Furnace Uses
Match the OEM part number on the motor, not the furnace model. Start with the Heil, Tempstar or Comfortmaker replacement blower motor page, or search the number in the ECM motor cross reference. United HVAC Motors sells remanufactured Genteq ECM blower motors only, so a furnace with a PSC blower motor needs a different part.
When to Call a Pro
Call a licensed technician for 5 flashes, 8 flashes, a tripped flame rollout switch, any gas valve work and any lockout that returns. The HVAC fault code lookup covers other brands, and Carrier owners can use the Carrier furnace and AC error codes guide.
FAQs
What does 4 flashes mean on a Tempstar furnace?
A limit or flame rollout switch is open. ICP lists a dirty filter, restricted ducts, a loose blower wheel and a defective blower motor among the checks.
What does 7 flashes mean on a Heil furnace?
The limit circuit stayed open too long and the control locked out. It auto-resets after one or three hours, depending on the control.
What does 6 + 1 mean on an ICP furnace?
Six short flashes and one long flash is an ignition lockout after the control runs out of retries. It auto-resets after three hours.
Do Comfortmaker and Arcoaire furnaces use the same codes?
Many share ICP controls, but modulating models and older boards differ. Confirm against the label inside your blower door.
Is 4 flashes always a bad blower motor?
No. It is a limit circuit fault, and the filter, ducts and venting are all on the list. Check them before condemning the motor.
